It has been long recognized that the internal vaginal cavity in its normal collapsed state is of much wider dimension in its transverse plane than in its vertical plane. It is equally well known that the minimum dimension of the vagina is near the introitus while the maximum dimension is near the cervix. It is desirable, therefore, when considering a tampon for catamenial use, to provide a structure which is in its initial state is of a size and/or shape to pass through the vaginal orifice without discomfort, and when once inside the vaginal cavity and beyond the restrictions of the orifice may be expanded, particularly in the lateral direction, to contact substantially all of surface of the vaginal walls from one side to the other in the vaginal cavity to prevent early bypass of the menstrual discharges from the cervix. Since the vaginal wall in its normal collapsed state is flaccid and has multiple folds and wrinkles which provide channels through which a significant portion of the menstrual fluids normally flow, it is also important that the absorbent tampon be as soft and conformable as possible, in order to conform to shape of the vaginal cavity and fit within these channels to minimize leakage.
The absorbent catamenial tampons now in general use comprise small, highly compressed, cylindrical plugs about three-eighths to one-half inch (about 1.0 cm to 1.3 cm) in diameter and from 11/2 to 21/2 inches in length (about 3.8 cm to 6.4 cm). Because of the need for absorbent capacity, they are usually formed from batts much larger in size than the vaginal orifice, and compressed to the small size indicated above in order to facilitate insertion. As fluid is absorbed, these compressed tampons are expected to re-expand toward their original pre-compressed size, and to eventually become large enough to effectively cover the vaginal cavity against fluid leakage or bypass. While it has been found that these compressed tampons perform their intended function tolerably well, even the best of them do not re-expand sufficiently, or fast enough, to provide good transverse coverage against leakage even though the vertical block may be satisfactory (although such vertical block may also be lacking). Further, most of these tampons often use only a small portion of their absorptive capacity before leakage. Since these tampons rely on some fluid absorption to re-expand, it is clear that fluid bypass and leakage can occur prematurely, and can particularly occur immediately following the time of insertion.
The prior art has long recognized that it is desirable to provide a tampon which is capable of immediately expanding after insertion, particularly in the lateral, or transverse direction. Immediate expansion of a catamenial tampon is most beneficially provided when it is not dependent on the absorption of bodily fluids for such expansion. "Dry expanding" is a term frequently used in the art to describe such a tampon.
Numerous attempts have been made to solve the problems described above with respect to a compressed cylindrical tampon through the use of a dry-expanding tampon. Some of these approaches focused on the applicator and others focused on the tampon itself.
For example, some approaches in the patent art suggest a tampon with a built-in mechanical expansion means, a typical example being U.S. Pat. No. 3,706,311 to Kohx et al. However, while a good transverse block appears to be produced, the mechanical expansion means disclosed in that patent is in the form of a flat springlike element which after insertion permanently maintains the spread configuration of the tampon, may make it difficult to remove.
Another approach is described in U.S. Pat. No. 3,512,528 to Whitehead et al, which teaches the use of a sack of absorbent material collapsed to a small size for insertion and which after insertion is expanded by the introduction of a gas or a fluid internally of the sack. The multiple steps and complicated manipulation of the gas or fluid introduction means required when using this type of tampon detract from what otherwise appears to be an effective solution of the problem.
Still another approach is described in U.S. Pat. No. 3,857,395 issued to Johnson, et al. The Johnson, et al. patent teaches the use of an elongated inserter device over which a flat tampon is draped. The inserter is said to permit the draped portion of the tampon to be pulled, rather than pushed into the cavity from the point at which the tampon is supported on the leading end of the inserter. The inserter means is equipped with a bilateral expansion mechanism which at the user's option may be operated to transversely spread the tampon at the time of insertion. The inserter device described in the Johnson, et al. patent suffers from many drawbacks, however. The Johnson inserter device is a complicated device comprising a pair of hinged arms that are capable of laterally diverging at a hinge or joint. The angular nature of the hinged arms would make that inserter uncomfortable to use. The complex nature of the hinged arms would also make it difficult and expensive to manufacture. As a result, it would not be suitable as a disposable applicator.
The prior art has recognized that a tampon should ideally be highly conformable and as non-rigid as possible. Such tampons, however, are difficult to insert and manipulate to an expanded position as the prior art attempts described above demonstrate. Therefore, all prior art attempts to provide a dry-expanding tampon have either required a complicated, cumbersome, and potentially uncomfortable application system, or have been constructed of a semi-rigid tampon or a tampon with a mechanical expansion mechanism.
Another series of attempts to overcome the problems associated with conventional, highly compressed, fluid expanding tampons is described in U.S. Pat. No. 3,749,094 issued to Duncan and U.S. Pat. Nos. 3,794,029 and 3,766,921 both issued to Dulle. The Duncan and Dulle devices are all generally conical and are designed to be dry-expanding. While these devices would be expected to overcome some of the problems associated with highly compressed, fluid expanding tampons, the Duncan and Dulle devices still require significant rigidity and compression in order to permit their use in a conventional "tube and plunger" type applicator for which they are designed. Such tampons are also constructed of absorbent polyurethane foam to provide the required inherent "spring."
It is desirable to provide a catamenial tampon which may be constructed of materials such as rayon and cotton which have long been used in the art for absorption of menstrual and other vaginal discharges. Such materials are accepted as safe and effective for such in-vivo application, are readily available, and are sufficiently inexpensive for disposable product application. It is also desirable to design a tampon which may be inserted digitally or through the use of conventional "tube and plunger" applicators since such applicators are well accepted by consumers and are easy and inexpensive to manufacture. It is also desired to provide a tampon in which at least a portion of the tampon is dry expanding to immediately cover a significant portion of the vaginal interior. Such dry expanding portion should be highly flaccid and conformable to conform to the surface of the vaginal interior.
The present invention seeks to combine the benefits of a conventional tampon comprised of an absorbent material compressed to a self-sustaining form, with the benefits of a dry-expanding tampon. One previous attempt to provide such a tampon is described in U.S. Pat. No. 4,212,301 issued to Johnson. The Johnson patent describes a digital tampon which has a portion made of absorbent material which is compressed to a self-sustaining form. An upper portion of the Johnson device is left uncompressed to provide a finger drape during digital insertion. While the Johnson device appears to combine some of the benefits of a conventional compressed tampon with the benefits of leaving an uncompressed portion, the Johnson device still suffers from some significant drawbacks. Portions of the Johnson device which are uncompressed, and therefore, potentially dry expanding are attached only to the top of the compressed portion. This restricts ability of the uncompressed portion to direct acquired fluid into the "core" portion of the tampon for long-term storage. Indeed, it appears from the Johnson disclosure, that the uncompressed portions serve to function as finger shields during insertion rather than as the unique fluid acquisition aids of the present invention.